Abstract

The biomass of all living organisms consists of approximately 30 out of 92 naturally occurring elements [1, 2]. Nitrogen and carbon are the only two elements that can be directly incorporated into biomass via microbial fixation of gaseous forms; N2, CO2, CO, CH4 and other hydrocarbons can be fixed into biomass. The remaining ∼28 elements required for life must be acquired from chemical species dissolved in water or in some cases can be solubilized from rocks and minerals. Nutrients by definition are essential elements or vitamins required for incorporation into cellular biomass, which distinguishes them from energy sources involved in cellular ATP generation. Nutrients may limit cellular growth due to low abundance and/or bioavailability. Extreme environments often possess unique chemical compositions due to extreme temperature or pH, producing nutrient-limited conditions. In some instances, nutrient limitation increases microbial sensitivity to other extreme conditions; for example, Deinococcus radiodurans exhibits increased radiation sensitivity when grown under nutrient limitation [3].